Xinjing News reported that 3 people were killed and 2 injured in the overturning accident of Jiangsu Wuxi 312 National Highway Viaduct on the evening of October 10. Today (October 11), Lu Hongkui, a bridge expert and director of bridge Research Institute of China Railway Bridge Science Research Institute, told the Beijing News that the accident could be preliminarily judged to be caused by the unbalanced load of overloaded vehicles. The incident viaduct was a single-pillar pier bridge, which is prone to overturning in case of overload and unbalanced load of vehicles.
Experts call the accident bridge a single-column pier bridge. If the load is too large, it will easily lead to the overturn of the box girder. Respondents Map
Single-column pier bridge is easy to overturn under overload and eccentric load
According to the Beijing News, at about 18:10 on October 10, three people were killed and two injured when a bridge overturned at K135 National Highway 312 and Xigang Road in Wuxi.
The Propaganda Department of Wuxi Municipal Committee reported that the overturning of the bridge was caused by overloading of transport vehicles after preliminary analysis by the accident investigation team.
Today, Lv Hongkui, a bridge expert and director of bridge Research Institute of China Railway Bridge Science Research Institute, analyzed the accident to reporters of the Beijing News.
Lu Hongkui said that according to the online public information and related news reports, preliminary judgment of the accident can be concluded that the most direct cause of bridge collapse is the overloading and unbalanced driving of trucks. He said that under the overloading and unbalanced loads of trucks, the force of bridges is unbalanced, resulting in rollover.
According to the failure patterns presented in the accident photos and videos, it can be inferred that the box girder is a three-span continuous prestressed concrete box girder. It is a straight bridge with double supports at both ends of the box girder. The pier top of the middle two piers only has a single support on the central line of the box girder, which belongs to the category of single-column pier bridges.
Lv Hongkui said that because single-column piers are supported by a single fulcrum in the transverse direction of the bridge, the lateral anti-overturning stability of the structure is very disadvantageous under the action of vehicle eccentric load.
According to other media reports, a senior construction science engineer who did not want to be named also said that the ramps connecting expressways and trunk roads in China are mostly single piers. The purpose is to make full use of the ground space, reduce land acquisition and reduce costs. But once a single pier encounters a weight far beyond the design load, the rigid body is more vulnerable to damage and overturning.
At the rescue site, the mechanical arm supports the overturning bridge body.
Every effort should be made to limit overloaded vehicles on the bridge
In recent years, bridge overturning accidents have occurred many times in China.
Lu Hongkui told the Beijing News that the final conclusions of the accident investigation were all related to the large overload and unbalanced load of vehicles (which caused the vehicle load to be 3 to 4 times the original design standard load), and most of the accident bridges were single-column pier systems.
After the overturning accident of single-pier bridges, relevant domestic administrative departments have issued corresponding policies, regulations and measures to eliminate the related hidden dangers. For example, Lv Hongkui will improve the safety factor of box girder against overturning in the design standard of bridge industry at present. In the design of new bridges, the structural form of single column pier is avoided as far as possible.
The safety factor of anti-overturning in the existing bridge design codes of the transportation industry is much higher than that in the past. He said.
New Beijing News reporters found that Yin Cunxin, Qin Dahang and Bao Qiwei of Beijing Municipal Engineering Design and Research Institute published the article Research on Overturning Resistance of Bridges Based on Torsion Failure on April 17, 2013. They pointed out that the main measures for overturning resistance design of single-column pier bridges are not only to take measures to increase the overturning stability of bridges in structural system, but also to do everything possible. Limit overloaded vehicles on the bridge.
The paper wrote: The damage to bridges caused by overloaded vehicles is one-time and irreversible. Road administration departments should manage the bridge scientifically, with clear rewards and penalties, strictly restrict overloaded vehicles on the bridge, let alone allow heavy vehicles to line up and drive side by side on the bridge.
In addition, it is also mentioned that due to serious overload and gaps in specifications, as well as the lack of previous design knowledge, there have been many accidents of roll, slip and overturn of single-column Supported Curved Bridges and single-column supported straight bridges across the country.
Lu Hongkui suggested that the existing single-pier bridges should be checked according to the new anti-overturning technical standards, and, if necessary, should be strengthened and reformed to improve the safety factor of anti-overturning.
From the perspective of urban management, the real-time monitoring and management of overloaded and overloaded vehicles on the bridge should be further strengthened in the future. He said that, at the same time, we should combine the current intelligent bridge monitoring, the Internet and the Internet of Things and other advanced technologies to identify and intercept overloaded vehicles in advance before they get on the bridge. In addition, the safety and health of bridge structures are monitored in time to avoid or reduce the occurrence of similar accidents.